Laparoscopic and endoscopic (“minimally invasive”) surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of minimally invasive surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).
These devices often perform a mechanical surgical action upon tissue, such as grasping, anastomosis, cutting, stapling, etc. A reliable approach is to mechanically implement such a capability through the limited confines of the elongate shaft. Much development has gone into integrating one or more motions through the handle and shaft to realize successful instruments.
For instance, surgical staplers include an end effector that simultaneously makes a longitudinal incision in tissue and applies lines of staples on opposing sides of the incision. The end effector includes a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.
Avoiding even extremely rare instances of equipment malfunction or human error is a highly desirable goal for minimally invasive instruments. To that end, many mechanical lockouts have been introduced. For instance, with regard to surgical staplers, it is known to mechanically lockout firing if a spent cartridge is present in the end effector or the end effector is not closed and clamped.
While such lockout mechanisms have certain advantages, it is desirable in some instances to provide an alternative or an additional lockout mechanism. Elaborate mechanical implementations often pose design challenges and introduce additional sources of failure or user complexity.
Consequently, a significant need exists for an improved surgical instrument that prevents inadvertent actuation.